Long Lost Sister
by Lady Vyxen
Summary: The Triwizard Tournament isn’t the only surprise that awaits for Harry and his friends. A pretty girl makes her appearance and claims to be his half sister. Will they believe her? A story with surprising plot twist.
1. Mary Augusta Potter

**Chapter 1 – Mary Augusta Potter**

He hated many things in his world. One of them were children, especially teenage girls who just reached puberty. Their giggles gave him headaches. He shuddered at the memory of his classmates. Making sure that his sleeves were down, he went into the night.

* * *

Mary always knew that she was pretty. People kept telling her that she was special and it only gave her more confidence. She wasn't afraid of many things and she loved evening walks. She heard that it helped her complexion stay unblemished.

She reached the road leading to her house, tired after long day. The lights were off on the street. Strange.

She hadn't much time to think as a man emerged from shadows, moonlight illuminated his face, twisted into ugly sneer.

She hadn't time to scream as he grabbed her roughly and shoved behind the corner. Then her world turned black and she knew no more.

* * *

Harry, Ron and Hermione were discussing Durmstrang. Well, more like Hermione explained everything she knew to them, as the door of their compartment slid open. There was a girl standing there and the boys' jaw's dropped slightly.

They weren't sure if it was because her jet black hair, or full, pink lips or big, brown eyes. For Hermione it looked like the girl liked the reaction she caused and she spoke after a moment.

"I was hoping to find you," she said in sweet voice, smiling at them. Well, mostly smiling at Harry, but did it matter?

"Oh, um…why?" asked Harry.

"May I come in?"

"Of course," blurted out Ron, causing Hermione to roll her eyes. She didn't like the look he send to that big-breasted girl.

"I'm Mary Augusta Potter," she said, again waiting for reaction to Hermione's irritation.

"Potter?" asked boys simultaneously.

"I- yes, Potter. Are you Harry?"

Harry cleared his throat. "Yes, I am Harry Potter."

"Can you tell me what's this strange coincidence with the same surnames?" asked Hermione, as eager as ever to find out what was going on.

"Yes, yes," said Mary quickly. "I'm a daughter of James Potter. It's a shame to admit, but my existence is a result of his infidelity."

"So you're my sister?" asked Harry, astonished. His eyebrows were nearly blended with his hairline, he raised them so high.

"Well, yes I am. I can't believe that I was finally attend Hogwarts," said Mary, lowering her head. When she lifted it again, her cheeks were flushed. "I hope that we will be good friends."

She smiled sweetly at them and then door slid open again, revealing Seamus, Neville and Dean.

Mary was introduced to boys who looked at her shyly. She seemed shy and confident; it switched back and forth in Hermione's opinion. She also often used the loo.

Some time later Draco Malfoy made an appearance and Mary proudly showed association with Harry and his friends, sending daring looks towards the blonde.

Draco seemed to not be immune to her charms as he was less nasty than usual, practically not taking his eyes off her.

* * *

"You should take the boat," said Hermione to Mary, as they stepped out of train. The bushy-haired girl gritted her teeth from the cold rain

"I do not think so," replied Mary, as sweetly as before.

She flicked her wand and after that her clothes seemed to be repelling rain drops. Of course, she was immune to Peeves' water bombs which made Ron completely drenched. Hermione didn't know that spell, but it could provide useful in situations like this one.

Professor McGonagall escorted Mary to the Great Hall and she was sorted first.

The black haired girl, who was supposed to be Harry's half sister had spent a ridiculous amount of time with the sorting hat on.

Finally it shouted "GRYFFINDOR," and Mary approached their table, grinning.

As before, all eyes were set on her until she plopped on seat, next to Neville Longbottom.

"What took you so long?" asked Dean, who was sitting on her other side.

"Oh, the Hat couldn't decide which house I should be in. It wanted to put me everywhere at once," answered Mary, giggling.

* * *

After the feast, Dumbledore explained to Harry, Hermione and Ron that Mary Augusta Potter was indeed his half sister and lived in hiding. Harry seemed doubtful; mostly because it meant that he couldn't date this girl.

"Professor Dumbledore told us that she's your family, Harry, and he's the wisest wizard alive! How can we doubt in what's he's telling us?" reasoned Hermione, who was completely convinced that Dumbledore's words were always right.

They went to the Gryffindor tower together.

Parvati and Lavender had a great giggling session, when Mary turned out to be so shy that she magicked her curtains shut.

Of course the girls tried to peek in, but the spell charmed the material to be completely impenetrable. Probably also soundproof, as there was no noise from inside.

"Stop being mean, girls," instructed them Hermione and rolled her eyes. It was just rude to treat a new person like that. Especially the one which was the only living family of her friend.

* * *

A/N: Thanks to Artemis J. Halk for beta reading this chapter :)

I couldn't stop myself from posting a Mary-Suish character with a twist. Things are not as simple as they appear to be and I hope that you'll stay with me for some time to learn about it :)


	2. Despicable Tendencies

**Chapter 2 – Despicable Tendencies**

The next day was less eventful. Somehow the strange, magnetic aura surrounding Mary had disappeared.

Harry felt like an idiot. He acted so stupid yesterday, and today… Mary was her nice old self.

She mostly listened rather than talked and wolfed down her food very much like Ron, which was surprising; she was thin, after all.

She didn't talk much about herself. When they were laughing in the common room and her chin started to tremble, she said it's a nervous tick.

Then she said that she had a pretty unpleasant life and wasn't ready to talk about that.

* * *

Neville was sitting with Mary in the library. He was working on the essay for Transfiguration, as well as most of people crowded there. He was unfortunate to sit not too far away from Malfoy and his goons, but Mary seemed unperturbed by their presence. She was chewing the end of quill and stoking her chin in absent-minded manner.

"Why are you not writing?" asked Neville, curious. He had his essay half-way done. He would have had it finished, but the Slytherins pushed past him and grabbed last book which was what he needed to finish it.

Mary shrugged and then took out a piece of parchment. Neville went back to work, but upon hearing her crumpling the parchment, he looked at her. She aimed it at Crabbe, who blinked as the paper ball hit him right between his eyes. Draco Malfoy turned in the opposite direction, wand ready. Mary put her hand, with wand, on her lap.

"_Accio essay_," she whispered and Malfoy's essay floated over to them and landed under their table. The blonde seemed unaware that his homework had just disappeared.

"Why did you do that?" asked Neville, seeing that Mary enchanted the essay. The penmanship changed into hers as well as 'D. Malfoy' morphed into 'M. Potter'.

"Because the dumb ass had it coming. Besides, I have more interesting things to do than writing stupid essays," she whispered.

Neville just sighed. He hated cheating like that. He had hardly any sympathy towards Malfoy, but Mary was being simply unfair.

Neville also wasn't a very lucky boy. As they left library, Malfoy cornered them in the corridor.

"Well, well Potter. It seems that you found a knight in shining armor. Too bad it's such a slip of a wizard."

Mary giggled. "Don't tell me that you would gladly trade places with him. Oh, maybe you would?"

Malfoy trained his wand at the both of them. "Looks like scarhead's little sister has a crush on me, doesn't it?" he asked smirking. Mary turned to Neville.

"Turn around and leave us," she said sweetly.

Neville had a determined look. "I won't leave you alone with him. He'll hurt you."

"I think I'll manage. Now go," she said in a demanding tone of voice.

Draco just raised an eyebrow, watching the cowardly Gryffindor making his retreat.

"So, your roaring lion curled up his tail and fled," he said. "All alone here on my mercy."

Potter's sister dropped her sweet look and her eyes turned empty and cold. Her features twisted into an ugly sneer and it looked weird on this innocent, pretty face.

"Listen, Malfoy," she said, advancing on him. "You think you can just walk in and push everyone around. But you're wrong and I'm warning you. _Behave."_

Draco gave a nod to Goyle. Fortunately, the fat boy knew what it meant and sent a bat boogey hex at Potter. She deflected it easily.

"You think that you're something special, but you're nothing more than annoying little shit."

"How dare you!" shouted Draco, but it came out higher than he would have liked. "My father-"

"Is another annoying little shit, thinking that he's _sooo_ important because he avoided Azkaban," she drawled. "There will be a day when he'll pay for all of this. There will be no reprieve," she said menacingly.

Draco sent a stinging hex towards her, but she was faster. She sent a jelly-legs jinx at the three of them and a good measure of stinging hexes as they fell to the floor.

"What in Merlin's beard is going on here?" they heard McGonagall's voice echoing in the corridor. Mary smiled towards Draco , but it was an unpleasant, nasty smile. Then her features became innocent again.

"Professor McGonagall, they cornered me and Neville and-"

"Miss Potter," said McGonagall, looking at the three Slytherins on the floor.

"I told Neville to run and I think I got lucky, but I was so scared!" she said, looking like was about to cry.

"It's all right Miss Potter. I can see that you were alone against three." She looked at the floor. "You should be ashamed, Mr. Malfoy. Detention for the three of you. It's unacceptable to ambush fellow students like this!"

Neville, who appeared a few moments after McGonagall, just clamped hand against his mouth. It seemed that he didn't need to feel guilty for leaving Mary alone.

* * *

Harry could tell that Snape's prejudice against him extended to his half sister. He was getting used to the idea that Mary was a part of his family and he was quite fond of her. She was a good listener, concerned more about his well being than hers and listened to him rather than speaking about herself.

He admired the fact that she could sympathize with him despite the fact that her past wasn't the most pleasant imaginable, at least from what she told him about it. He found it hard to believe that his father could have had an affair while being with his mum, but honestly - he didn't know his father much more than from few photographs and bits of information provided by Remus or Sirius.

Today's potion wasn't exceptionally difficult, and Mary managed to do it quite well. She was paired with Ron, but since they sat close to each other, he could see the contents of her cauldron.

It looked quite good, according to Hermione, who was sitting with him this time.

Snape leaned above the black haired girl and his face turned into an ugly sneer.

"Miss Potter, you seem to be convinced that if your potion is done quite well, you have every right to show your bosom to as wide audience as you can get."

"No, professor," she said quietly, but her face was visible to him and her expression towards Snape – loathing. It was nothing strange; he had the same expression every time he entered the damp, dingy classroom.

"Button up your school uniform and ten points from Gryffindor," said Snape silkily, and turned to inspect Goyle's cauldron.

"Why can't he leave my tits alone? It's not like I'm commenting on his balls," muttered Mary and Harry snorted.

"Do you have anything to add Miss Potter?" asked Snape who suddenly was looming above Mary again.

"Asshole," she muttered.

"I beg your pardon?" Snape almost whined.

"I said _no_, professor," she replied calmly.

"Listen, you insolent girl. Whatever you're trying to do to impress your dim-witted classmates is not working," hissed Snape. Anger was radiating off him.

Harry sank deeper in his chair, thanking whatever Gods that may listen that he wasn't the one who provoked it.

He heard a bubbling sound somewhere behind him and turned to see violent fumes from Parvati's cauldron.

Snape needed no encouragement to be extra nasty. He vanished the contents of her cauldron before the vile substance had any chance to explode.

Pansy had a nasty smirk plastered on her face and Harry could tell why Parvati's potion was ruined.

"Well, well, Miss Patil. It seems that you share the same brain cell with Miss Potter. What a shame that you're not the one using it today," said Snape with mock concern in his voice.

Parvati became red. "It was Parkinson, sir!"

"Miss Parkinson borrowed the brain cell today? Ten points from Gryffindor for ruining a simple potion."

Parvati was shaking. It looked that she was having a bad day and didn't care about house points. Hermione looked devastated. Everything she earned in Transfiguration and History of Magic was gone. At this rate, they would have negative points before Christmas.

"That's unfair! You did it on purpose!" shouted Parvati and Snape just raised an eyebrow. He then leaned towards her, placing both hands on her worktable.

"I've dealt with dunderheads like you longer than you can picture it in your imbecilic, little head. I won't let you ruin my lessons or accuse me of being fair or not. It's not your business, you're not the headmaster. If you have any complaints, go and visit him. Don't forget to mention jeopardizing you fellow students with your terrible lack of potion making skills. Detention, Miss Patil, every Thursday until Christmas break."

Parvati's eyes became round like saucers. She clamped her hand against her mouth and fought hard not to cry.

"You can leave the classroom and go wreak havoc elsewhere," added Snape.

Pansy watched the girl leave the classroom curiously. Someone had a good idea throwing acid pops in her cauldron. She was sure that it was Draco's brilliant work.

Contrary to the popular belief, Pansy didn't hate Gryffindors. Hogwarts would be boring without them.

* * *

A/N: Thanks to **Artemis J. Halk** for beta reading this chapter.

Sooo…how do you like it? :)


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